1. Field of the Invention
The present invention relates in general to an engine of a small watercraft, and in particular to a fuel supply system for a watercraft engine.
2. Description of Related Art
Personal watercrafts have become popular in recent years. This type of watercraft is sporting in nature; it turns swiftly, is easily maneuverable, and accelerates quickly. Personal watercraft today commonly carrier one rider and one or two passengers.
A relatively small hull of the personal watercraft defines an engine compartment below a riders area. An internal combustion engine frequently lies within the engine compartment in front of a tunnel formed on the underside of the watercraft hull. The internal combustion engine commonly powers a jet propulsion device located within the tunnel. An impeller shaft commonly extends between the engine and the propulsion device for this purpose.
Personal watercrafts often employ an in-line, multi-cylinder, crankcase compression, two-cycle engine. The engine conventionally lies within the engine compartment with the in-line cylinders aligned along a longitudinal axis of the watercraft hull (in the bow to stein direction).
A dedicated carburetor usually supplies fuel to each cylinder of the engine. Because of the sporting nature of the watercraft and the tendency for frequent, abrupt directional changes of the watercraft when used, prior personal watercraft engine employ floatless-type carburetors. A fuel system used with the floatless-type carburetors continuously supplies fuel from a fuel tank to the carburetors while returning excess fuel to the fuel tank.
Though floatless carburetors improve fuel delivery to the engine's intake, prior fuel supply systems have not been so immune to abrupt directional changes. The fuel pick-up port in the fuel tank often is exposed to air when the watercraft leans in a turn, especially when the fuel level within the tank is low. Air in the fuel line produces a number of adverse affects. The fuel/air ratio of the charge delivered to the engine cylinders is reduced which results in poor engine performance. Air in the fuel line also can destroy the fuel pump's prime, as well as cause some fuel pumps to run hotter and damage the pump either immediately or over time (i.e., reduce the pump's durability).
Carburetored engines also tend to produce a fuel charge of a less than accurate fuel/air ratio. Consequently, engine performance is not optimized under all running conditions and greater pollutants can result.